Circuit breaker with an undervoltage trip device

ABSTRACT

A CIRCUIT BREAKER COMPRISING A PAIR OF SEPARABLE CONTACTS AND AN AUTOMATICALLY RESETTABLE MECHANISM, INCLUDING A LATCH, FOR OPENING AND CLOSING THE CONTACTS. AN ELECTROMAGNETIC DEVICE ASSOCIATED WITH THE MECHANISM FOR TRIPPING THE LATCH AND AUTOMATICALLY OPENING THE CONTACTS. THE ELECTROMAGNETIC DEVICE COMPRISING A SOLENOID COIL AND AN ARMATURE-LIKE MEMBER ENGAGEABLE WITH THE LATCH TO UNLATCH THE MECHANISM WHEN THE CONTACTS ARE CLOSED. A MAGNETIZABLE CORE DEVICE ACTUATABLE BY THE COIL TO RELEASE THE ARMATURE-LIKE MEMBER AND PERMIT IT TO MOVE AWAY FROM THE LATCH WHEN THE COIL IS ENERGIZED ABOVE A PREDETERMINED LEVEL AND FOR MOVING THE ARMATURELIKE MEMBER INTO ENGAGEMENT WITH THE LATCH WHEN THE COIL IS ENERGIZED BELOW A PREDETERMINED LEVEL AND THE CONTACTS ARE CLOSED. FURTHER, SUCH CIRCUIT BREAKER MAY BE USED IN COMBINATION WITH A KNOWN CIRCUIT BREAKER WHICH SENSES AN INCREASE IN ENERGIZATION TO PROVIDE A TWO POLE UNIT ONE OF WHICH IS SENSITIVE TO AN INCREASE IN ENERGIZATION AND THE OTHER WHICH IS SENSITIVE TO A DECREASE IN ENERGIZATION.

Jan. 26,: 1971 A. r. ELLIS, JR 3,559,125

CIRCUIT BREAKER WITH AN UNDERVOLTAGE TRIP DEVICE Filed Jan 15, 1969 v 4 Sheets-Sheet 1 I 8 f v 1 Z0 0 94 91 I 4/ J r T x j 5-6 40 3/ 99 47 54 r O 52 4a 36 fx'eyG 8/ 89 i M //l/V/V70/e 8/ v fl u e ELL l5 85 ///s fi m-Mfrs.

Patented Jan. 26, 1971 3,559,125 CIRCUIT BREAKER WITH AN UNDERVOLTAGE TRIP DEVICE Arthur T. Ellis, Jr., Levittown, Pa., assignor to Heinemann Electric Company, Trenton, N.J., a corporation of New Jersey Filed Jan. 15, 1969, Ser. No. 791,397 Int. Cl. H01h 83/06 US. Cl. 335-20 18 Claims ABSTRACT OF THE DISCLOSURE A circuit breaker comprising a pair of separable contacts and an automatically resettable mechanism, including a latch, for opening and closing the contacts. An electromagnetic device associated with the mechanism for tripping the latch and automatically opening the contacts. The electromagnetic device comprising a solenoid coil and an armature-like member engageable with the latch to unlatch the mechanism when the contacts are closed. A magnetizable core device actuatable by the coil to release the armature-like member and permit it to move away from the latch when the coil is energized above a predetermined level and for moving the armaturelike member into engagement with the latch when the coil is energized below a predetermined level and the contacts are closed. Further, such circuit breaker may be used in combination with a known circuit breaker which senses an increase in energization to provide a two pole unit one of which is sensitive to an increase in energization and the other which is sensitive to a decrease in energization.

BACKGROUND OF THE INVENTION This invention relates to electromagnetic devices and, in particular, to circuit breakers in which the sensing of an electrical condition is accomplished electromagnetically by a device which includes an armature pivoted in tripping relation with a mechanism to open its contacts at such time. Such devices are illustrated, for example, in United States Pat. No. 2,360,922, issued to Kurt W. Wilckens, and United States Pat. No. 3,329,913, issued to William W. Camp.

These prior patents relate to an electromagnetic sensing device including a solenoid coil, a time delay tube housing a movable core of magnetizable material "movable against the retarding action of a liquid and a pivotal, spring biased, armature to provide a time delay upon the occurrence of an overload which, if below a certain value and if it does not persist for a predetermined time, will not cause the tripping by the armature of the circuit breakers operating mechanism and will not open the circuit breaker contacts, thereby avoiding nuisance tripping. In this type of circuit breaker if the overload current is sufficiently high, the resulting magnetic flux will substantially instantaneously cause the pivotal armature to pivot and trip the circuit breaker operating mechanism and will open the circuit breaker contacts substantially instantaneously, i.e., with no intentional time delay.

It is an object of this invention to modify this type of electromagnetic device mechanism so as to provide a circuit breaker which is sensitive to a drop in the level of energization of the coil and to provide for the opening of the contacts at such time.

It is another object of this invention to modify this type of electromagnetic device in such a way that the resulting circuit breaker may be associated with the previously known type to provide a multipole circuit breaker one of whose poles will be sensitive to an increase in energiza- Rice tion and the other of whose poles will be sensitive to a decrease in energization thereof.

BRIEF SUMMARY OF THE INVENTION This invention is embodied in an electrical circuit breaker having separable contacts actuatable by a linkage including a toggle and a latch. The latch, on predetermined current conditions, is tripped by a pivotal, armature-like member. The armature-like member forms part of the electromagnetic device which further comprises a frame and a solenoid coil. The solenoid coil partially surrounds a tube housing a core of magnetizable material which is biased toward one end, the rear end, of the tube. The other, or forward, end of the tube includes a magnetizable pole piece toward which the core moves upon sufiicient energization of the coil.

The armature-like member biased away from the pole piece and away from engagement with the latch, but is connected to the core so that the core may move the armature-like member into tripping engagement with the latch.

The core is biased away from the pole piece by a compression spring. The core is moved by the coil toward the pole piece upon energization of the coil above a predetermined level to compress the spring and release the armature-like member, permitting it to move away from the latch. Upon a subsequent predetermined drop in the level of energization of the coil, the compression spring forces the core away from the pole piece and the core at such time actuates the armature-like member causing it to trip the latch and open the contacts.

The foregoing and other objects of this invention, the principles of this invention and the best modes in which I have contemplated applying such principles will more fully appear from the following description and accompanying drawings in illustration thereof.

BRIEF DESCRIPTION OF THE VIEWS half-cases of the circuit breaker being removed to show the internal parts of the circuit breaker, the contacts being shown in the closed position and the coil being fully energized;

FIG. 2 is a view similar to FIG. 1, but the contacts are shown in the open position, while the coil is fully energized; I

FIG. 3 is a view similar to FIG. 1 but showing the trip-free position, i.e., the coil has been deenergized sufficiently to pivot the armature-like member toward the pole piece, the handle is held in the On position of the -contacts, but the toggle mechanism has collapsed, and

the contacts are open;

FIG. 4 is a partial sectional view taken through the coil, partially showing the frame and partially showing the armature-like member in the position corresponding to that shown in FIG. 3;

FIG. 5 is a top view taken along the line 55 in FIG. 4;

FIG. 6 is a perspective view of the armature-like member;

FIG. 7 is a view similar to FIG. 3 of the invention as embodied in a two pole circuit breaker but showing only the circuit breaker pole which senses deenergization of the coil below a predetermined level; and

FIG. 8 is a partial sectional view taken along the line 88 in FIG. 7 and showing the common trip means connecting the two poles of the two pole circuit breaker.

DETAILED DESCRIPTION Referring to the drawings, a circuit breaker 10 is shown comprising a case 11 formed by two juxtaposed,

approximately half-cases 16, only one of which is shown in FIG. 1, secured together by rivets 18, the case 11 being formed of suitable electrical insulating material.

The circuit breaker includes an automatically resettable linkage mechanism which is mounted within the case 11 and a handle 21 extends through the case 11 and forms part of the linkage mechanism 20.

The mechanism 20 further includes a movable contact carried by a movable arm 31 and engageable with a stationary contact 32, the latter being carried by a terminal 33. The movable arm 31 is connected by a flexible conductor 36 to another terminal 34, as shown. A coil 40, formed about a spool 39, forms part of an electromagnetic device 41 which is also enclosed by the case 11 and which is associated with the linkage mechanism 20 to trip open the contacts 30 and 32 on a predetermined level of deenergization of the coil 40, i.e., on predetermined undervoltage or no voltage conditions. The coil has its end portions connected to terminals 44 and 45, as shown. The terminals 33, 34 and 44, 45 extend outwardly from the base of the circuit breaker as more fully described in connection with Pat. No. 3,329,793 and FIG. 6 thereof.

Further, the movable arm 31 is biased by a spring 47 toward the open position of the contacts 30 and 32 and the movable arm 31 is mounted on a pin 48 about which it pivots, the pin 48 having end portions carried by two spaced frame plates 50 and 51 which are integral with an L-shaped member 52 and jointly form a frame 53 carrying the spool 39 and the coil 40. (FIGS. 1, 2 and 3 show only the frame plate 50, both frame plates 50 and 51 being partially shown in FIG. 5.) The end portions of the pin 48 extend into holes (not shown) formed in the opposed side walls of the case 11 to locate the mechanism relative thereto.

The movable arm 31 is also connected by a pin 54 to an automatically relatchable toggle assembly 56, the latter being in turn connected to the handle 21 by a pin 58. The automatically relatchable toggle assembly 56 is provided with a lock assembly 57, including a spring 61 to bias the lock assembly to the latching position, as described in greater detail in Camp Pat. No. 3,329,913. The handle 21 pivots about a pin 60 having end portions carried by the spaced frame plates 50 and 51, the end portions of the pin 60 extending beyond the frame plates into holes (not shown) formed in the opposed side walls of the case 11 to locate the mechanism relative thereto. Also, the pin 60, for the handle 21, also carries a coil spring 93 biasing the handle to the contacts open position.

The movable arm 31 also carries a pin 62 having end portions which engage the frame plates 50 and 51 to limit opening movement of the arm 31, as shown in FIG. 2.

The structure heretofore generally described is disclosed in greater detail in Camp Pat. No. 3,329,913. This invention is concerned with modifying the electromagnetic device 41 so as to provide a core device 42 (FIG. 4) that will trip the mechanism 20 when the coil 40 is deenergized to a predetermined level, i.e., to sense an undervoltage or no voltage condition, as hereinafter described in further detail.

The core device 42 (FIG. 4) includes a tube 64 extending through the horizontal leg 65 of the frame 52, the tube 64 (FIG. 4) housing a core or plunger 66 biased toward the lower end of the tube '64 by a spring 67, the core 66 being of magnetizable material and being movable upwardly against the retarding bias of the spring 67 upon sufiicient energization of the coil 40 by the electromagnetic flux created at such time.

The tube 64 carries a pole piece 70 of magnetizable material at its upper end and is closed at its lower end by a cap 72, both being preferably soldered to the tube 64, the tube 64 and cap 72 being preferably of non-magnetizable material. Also, the tube 64 is secured to the 4 horizontal leg 65 of the frame 53 such as by being soldered thereto.

The core 66 is biased away from the pole piece 70, i.e., downward as viewed in FIG. 4, by a compression spring 67. The compression spring 67 has one end seated on a shoulder 75 formed at the jointure between the larger, lower end portion 78 of the core 66 and the upper smaller end portion 77 thereof.

The upper end of the spring 67 is seated against a washer 76 which is in turn biased by the spring 67 against the pole piece 70. The washer 76 fits loosely within the tube 64 and is held in place by the spring 67, the washer 76 being preferably of a plastic material, such as Teflon.

The washer 76 cushions the impact of the core 66 when it is moved upward toward the pole piece 70 on sufficient energization of the coil 40 and also provides a magnetic gap between the pole piece 70 and the core 66. Such a magnetic gap assures that the core 66 will move away from the pole piece 70 quickly, without hesitation, when the energization of the coil 40 is reduced sufficiently. Otherwise, residual magnetism may slow down the movement of the core 66 at such time or if the drop in energization is not too great, it might keep the core 66 from moving at all.

The core 66 is connected to an armature-like pivotal member 84 by a pin 80, the pin being preferably of non-magnetizable material, such as brass, and carried by the upper, forward core portion 77. The pin 80 may be pressed into a suitable hole in the forward core portion 77 and extends loosely through suitable aligned holes in the Washer 76 and the pole piece 70 and through a slot 85, FIG. 6, in a head 83 of the armature-like member 84 to actuate the latter when the energization of the coil 40 drops below a predetermined level. To actuate the armature-like link 84 the pin 80 has secured to its upper end portion, above the head 83, a collar 87, the collar 87 being secured to the pin 80 such as by being soldered thereto.

The armature-like member 84, in addition to the head 83, comprises an integral trip finger 86, a balance arm 88, and a sprocket arm 89, FIG. 6. The armature-like member 84 has suitable holes 81 through which extends a pin 91, FIG. 1, which has end portions supported by the spaced frame plates 50 and 51, the armature-like member 84 being biased clockwise by a spring 92 which is carried by the pin 91 and which has one end secured to the sprocket arm 89, FIG. 6, and its other end hooked over the frame plate 50, FIG. 1.

It will be understood that the various parts are proportioned so that when the core 66 is in its lowest position, FIG. 4, the collar 87 has moved the head 83 of the armature-like member 84 toward the pole piece 70 suf ficiently for the trip finger 86 to be moved into unlatching position with the lock arm 90. Similarly, when the core 66 is raised by the coil 40 to its highest position, FIGS. 1 and 2, the collar 87 is raised sufiiciently to release the head 83 of the armature-like member 84 and permit the member 84 to pivot clockwise suificiently to move the trip finger 86 out of its unlatching position with the lock arm 90, whereby the contacts 30 and 32 may be closed.

When the handle 21 is rotated clockwise, FIG. 2, the toggle assembly 56 and the movable arm 31 all move down, against the bias of the opening spring 47, and move the contact 30 into engagement with the stationary contact 32, achieving the closed contacts position, illustrated in FIG. ,1.

If, prior to the closing of the contacts 30 and 32, the coil 40 is sufficiently energized to pull the core 66 up against the bias of the spring 67 from the position shown in FIG. 4 to that shown in FIG. 1, the armature-like member 84 will have been moved from the position shown in FIGS. 3 and 4 to that shown in FIG. 1 in which position the trip finger 86 is slightly spaced from, or barely touching, the arm 90 of the latch or lock assembly 57.

However, if the coil 40 is not sufliciently energized to pull the core 66 up against the bias of the springs 67 sufiiciently to release the armature-like member 84, the closing of the contacts 30' and 32 will not take place, or if it takes place will not be maintained, as the trip finger 86 will then engage the arm 90 and pivot it in the direction to unlatch the lock assembly 57.

Assuming that the coil 40 is sufliciently energized to pull the core 66 up to the position shown in FIGS. 1 and 2, when the handle 21 is moved to the contacts closed position, the circuit breaker will assume the position illustrated in FIG. 1. If now the coil 40 is deenergized to a level such that the magnetic flux thereby created is insufficient to maintain the core 66 raised against the downward force thereon of the spring 67, the core 66 will move downward (under pressure of the spring 67) and the collar will engage the head 83, pivoting the armature-like member 84 counterclockwise from the position shown in FIGS. 1 and 2 to that shown in FIGS. 3 and 4. Such pivoting of the armature-like member 84 causes the trip finger 86 to engage the arm 90 rotating the latter in the direction to unlatch the toggle assembly 56, whereupon the toggle assembly 56 collapses under pressure of the opening spring 47 and the contacts 30 and 32 open, the handle 21 pivoting to the open position of the contacts.

A shunt plate 94 may be added to the frame 53 to increase the magnetic force on the core 66 for a given energization of the coil 40. The frame 53 may also be of the type in which the horizontal leg 65 has an upstanding tubular portion 96 which extends centrally into the spool 39.

The armature-like member 84 should preferably come to rest, when in the position shown by FIG. 4, with a slight space 97, FIG. 4, between the undersurface of the head 83 and the upper surface of the pole piece 70. Such slight space 97 may be provided by limiting counterclockwise (FIG. 4) movement of the head 83 by having it engage with the upper end portion of the vertical leg 98 of the frame 53. The space 97 is provided, to prevent a magnetic coupling from developing between the head 83 and the pole piece 70 tending to retain the armature in the position shown in FIG. 4 after energization of the coil. Providing the space 97 between the armature-like member 84 and the pole piece 70 applies when the armature-like member 84 is of magnetizable material such as steel, but is not applicable if the armature is made of a non-magnetic material such as brass. As the armature-like member 84 is usually made of steel in other type circuit breakers, I prefer the use of steel.

It has been previously stated that the trip finger, when in the position of FIG. 1, should be close to or barely touching the arm 90 of the lock assembly 57. Likewise, the collar 87, carried by the pin 80 should also be close to or barely touching the upper surface of the head 83. The reason for this is that the force stored and provided by the compression spring 67 is at a maximum when the core 66, FIG. 4, pin 80 and collar 87, FIG. 1, first start to move down. By providing no clearance, or a minimum clearance, between the collar 87 and the head 83, FIG. 1, and between the trip finger 86 and the arm 90, the maximum spring force is used to unlatch the toggle assembly 56.

Referring to FIGS. 4 and 5, the shunt plate 94 is made sufficiently large to shunt the magnetic flux from the armature-like member 84. The shunt plate 94 is preferably abutted against the vertical leg 98 to thereby close the magnetic circuit about three sides of the coil 40, as shown in FIG. 4.

Preferably the core 66 has a stepped cylindrical shape, as shown, and fits sufficiently loosely within the cylindrical tube 64 to create no dash pot action which would tend to retard movement of the core 66. The pole piece 70 and washer 76 are also circular in shape and are provided preferably with circular holes through which the cylindrical pin 80 loosely extends.

To minimize and/ or extinguish any are that may form between the contacts 30 and 32 whenever the contacts are opened, assuming the contacts to be energized, a stacked array of three magnetizable, metal grids 99 are supported within the case 11 and about the stationary contact 32, as known in the art.

Thus, if the terminals 44 and 45 are first connected to a source of potential to be monitored which is sufiicient to energize the coil 40 to a level which creates a sufficient electromagnetic flux to raise the core 66 against the downward bias of the spring 67, and to thereby raise the pin 80 and the collar 87 to the position shown in FIGS. 1 and 2, thus permitting the armature-like member 84 to be pivoted by its spring 92 from the position shown in FIG. 3 to that shown in FIG. 1, the handle 21 may then be moved from the position shown in FIG. 2 to that shown in FIG. 1 and the contacts 30 and 32 will be closed.

When the energization of the coil 40 reduces to a predetermined level, i.e., when an undervoltage occurs, as when the power supply thereto is interrupted for any reason, the electromagnetic flux produced by the coil 40' decreases. When the electromagnetic flux decreases to an extent that the magnetic force holding the core 66 up, in the position of FIG. 4, is less than the force downwardly exerted on the core 66 by the spring 67, the core 66 will move downwardly. The downward movement of the core 66 carries with it the pin 80 and the collar 87 which in turn engages the head 83 and pivots the armature-like member 84 from the position shown in FIG. 1 to that shown in FIG. 3, moving the head 83 toward the pole piece 70 and the trip finger 86 into engagement with the arm 90 of the lock assembly 57 to turn the latter so as to unlatch the toggle assembly 56, whereupon the toggle assembly 56 collapses under pressure of the opening spring 47 and the contacts 30 and 32 open.

So long as the power is interrupted to the coil 40, i.e., so long as the coil 40 is energized below a predetermined level, the circuit breaker contacts 30 and 32 cannot be reclosed. If the handle 21 is moved to the closed contacts position at such time, since the trip finger 86 is in its unlatching position, it will trip the lock assembly 57, causing the toggle assembly 56 to collapse, and this position is shown in FIG. 3.

As the core 66 moves up and down it may have a tendency to rotate relative to the tube '64. By providing a circular collar 87 of a diameter larger than the width of the slot 85, in the head 83 of the armature-like member 84, should rotation of the core 66 take place, the pin and the collar 87 will rotate freely without jamming in the slot 82.

Also, by sloping the trip finger '86 downwardly, away from the lock arm 90, a sufficient amount, if the linkage mechanism is attempted to be reclosed, while the core is in the position shown in FIG. 4, i.e., while holding the armature-like member 84 rotated counterclockwise to its full extent, the arm 90 will freely ride off the trip finger 86.

It has been found that the invention is applicable to alternating current, rectified direct current or direct current for use in the coil 40.

Also, it will be noted that the invention provides an arrangement which is operative no matter in what position the circuit breaker is mounted.

Referring to FIGS. 7 and 8 the invention is embodied in a two pole circuit breaker comprising a voltage sensing circuit breaker 112 and a series, overload current sensing circuit breaker 114, the latter being only partially shown in FIG. 8, but the two circuit breakers 112 and 114 being placed in side-by-side relation, as shown in Camp et al. Pat. No. 3,299,231. The voltage sensing circuit breaker 112 shown in FIG. 7 is constructed essentially the same as that described previously in connection with FIGS. 1 to 6, but is in addition provided with a common trip means for interconnecting the two circuit breakers 112 and 114 and providing for the tripping of one of the circuit breakers when the other circuit breaker trips.

While not illustrated in detail; the circuit breaker 114 is constructed similar to the circuit breaker illustrated and described in connection with Camp Pat. No. 3,329,913.

The circuit breaker 112 is generally similar to that described in connection with FIGS. 1 to 6 and comprises a case 121 enclosing an automatically resettable linkage mechanism 122 and a handle 123 extending through the case 121, as shown in FIG. 7. The linkage mechanism 122 includes a movable contact 124 carried by a movable arm 125 and engageable with a stationary contact 126. The linkage mechanism 122 includes a toggle assembly 128 and a lock assembly 129, the same as that described in connection with FIGS. 1 to 6.

The circuit breaker 112 also includes an electromagnetic device 131 constructed in accordance with the description of the electromagnetic device illustrated in connection with FIGS. 1 to 6. The electromagnetic device 131 includes a coil 136, a core device 132 and an armature-like member 134 having a trip finger 135 engageable with the lock assembly 129'.

The coil 136 is connected to the circuit which is to be monitored by terminals 137 and 138, and the movable and stationary contacts 124 and 126 are connected to another circuit by terminals 140 and 141, respectively.

The circuit breaker 112 has a spring pin 160 carried by the movable arm 125 to limit pivotal motion of the arm 125 by abutment with the frame plates 180, as shown in FIG. 7. The spring pin 160 has a slot within which are inserted leaf actuators 163 at opposite ends of the pin 160, only one actuator being shown in FIG. 7. The leaf actuators 163 abut a common trip member 170 to transmit the opening movement of the movable arm 125 to the common trip means 120. The common trip member 170 is mounted on the outer sides of the frame plates 180, as shown in FIG. 8, and is pivotally carried by a pin 175, FIG. 7, about which also pivots the armature-like member 134. The common trip member 170 comprises two arms 173 and 174 on opposite sides of the frame plates 180, the latter being part of the frame 181, and the leaf actuators 163 engage the arms 173 and '174 on opposite sides of the frame plates 180. The arms 173 and 174 are interconnected by a bar 182 which has a hole 184, FIG. 8, extending through it.

The circuit breaker 114 has a common trip member 200 constructed, supported and actuated the same as the common trip member 170.

A rod 202 interconnects the common trip members 170' and 200 for joint rotation upon the pivotal movement of one of them, the rod 202 extending through the hole 184 in the bar 182 and a similar hole 204 in the corresponding bar 206 of the common trip member 200*, and through suitable openings 207 in the cases.

Referring to FIG. 8, in which the coils and spools of the electromagnetic devices have been omitted for clarity, it will be noted that the bars 182 and 206 rest upon the heads 208 and 210 (FIG. 8) of the armature-like members 134 and 210 of the circuit breakers 112 and 114. Insofar as the circuit breaker 114 is concerned the member 210 is in fact an armature, of an electromagnetic device 216 including a frame 218 and frame plates 219, most of the electromagnetic device 216 not being shown, but being illustrated and described in Camp Pat. No. 3,329,913. Further, the arms 173 and 220 engage ears 224 and 226, respectively, formed on the heads 208 and 210, so that when the actuators rotate the common trip members 170 and 200, the motion of the common trip members is transmitted to the armature-like members.

Preferably, the common trip members 170 and 200 are made of electrical insulating material, such as the plastic Lexan and the interconnecting rod 202 is also preferably of electrical insulating material, such as a phenolic plastic.

The common trip means 120 briefly described heretofore is of the type described in detail in Schwartz Pat. No. 3,098,910, Schwartz et al. Pat. No. 3,098,911 and Sprague Pat. No. 3,098,912.

Having described this invention, what I claim is:

1. A circuit breaker comprising:

a pair of separable contacts,

a mechanism for manually opening and closing said contacts,

said mechanism including an opening spring for biasing said contacts to the open position, said mechanism including a lock assembly to maintain said mechanism latched when said contacts are closed, electromagnetic means associated with said mechanism for tripping said lock assembly and automatically opening said contacts,

said electromagnetic means comprising:

a solenoid coil,

a member engageable with said lock assembly to unlatch said mechanism when said contacts are closed,

a magnetizable frame about said coil, and

a magnetizable core means actuatable by said coil to release said member and permit said member to move away from said lock assembly when said coil is energized above a predetermined level and for moving said -member into engagement with said lock assembly when said coil is energized below a predetermined level and said contacts are closed.

2. The combination recited in claim 1 wherein said mechanism is automatically resettable.

3. The combination recited in claim 2 wherein said coil includes a pole piece, said core means includes a core and a compression spring biasing said core away from said pole piece, said core being moved toward said pole piece upon energization of said coil above a predetermined level to compress said spring and release said member, whereby upon a subsequent predetermined drop in the level of energization of said coil, said compression spring forces said core away from said pole piece and said core at such time actuates said member causing said member to actuate said lock assembly to open said contacts.

4. The structure recited in claim 3 wherein said electromagnetic means further includes a tube of non-magnetizazle material within which said core is movable, said pole piece being secured to one end of said tube, and said compression spring being within said tube between said pole piece and said core.

5. The structure recited in claim 4 wherein said electromagnetic device further includes a washer of non-magnetic material between said pole piece and said core, said core seating against said washer when said core has moved its full extent toward said pole piece.

6. The structure recited in claim 5 wherein said washer is made of plastic material capable of cushioning the impact of said core against said washer and providing a magnetic gap.

7. The structure recited in claim 4 wherein said electromagnetic means includes a U-shaped frame on three sides of said coil for substantially shunting the electromagnetic flux from said member.

8. The structure recited in claim 4 wherein said electromagnetic means includes a connector secured to said core and extending through said pole piece, said member being biased away from said pole piece, said connector providing for joint movement of said core and said member when said core moves away from said pole piece, but releasing said member for movement away from said pole piece when said core moves toward said pole piece.

9. The structure recited in claim 6 wherein said electromagnetic means includes a U-shaped frame on three sides of said coil for shunting the electromagnetic flux from said member.

10. The combination of:

a plurality of similar switch units,

each switch unit having a pair of relatively movable contacts,

an automatically resettable mechanism including:

a toggle linkage operatively connected between one of said contacts and a manual operator, an electromagnetic toggle tripping device associated with each toggle linkage,

said toggle linkage being collapsible by said device to a position for opening said contacts, an automatically resettable movable common trip means associated with all of the tripping devices and having a common trip member associated with each switch unit, whereby the opening of said contacts of one switch unit moves the common trip members of the associated switch units in the direction necessary to cause their associated toggle linkages to also collapse and move to the contacts open position, one of the electromagnetic toggle tripping devices of the switch units being responsive to a predetermined drop in energization thereof.

11. The structure recited in claim wherein the electromagnetic tripping device responsive to a predetermined drop in energization thereof includes a coil and a core, a spring engaging said core, an armature-like member, said coil when sufficiently energized moving said core in one direction to a first position in which said core releases said armature-like member from tripping engagement with said mechanism, and when said coil is sufficiently deenergized, said spring moving said core in the opposite direction to a second position during which said core moves said armature-like member into tripping engagement with said mechanism.

12. The structure recited in claim 10 wherein another of the electromagnetic toggle tripping devices of the switch units is responsive to a predetermined increase in energization thereof.

13. The structure of claim 11 wherein another of the electromagnetic toggle tripping devices of the switch units is responsive to a predetermined increase in energization thereof.

14. The combination of:

a plurality of similar switch units,

each switch unit comprising an electromagnetic device including:

an armature-like member and a coil for actuating said armature-like member upon predetermined electrical conditions, relatively movable contacts, an automatically resettable linkage mechanism movable to open and close said contacts and biased to the contacts open position,

said linkage mechanism including a latch for maintaining said linkage mechanism in the contacts closed position, said armature-like member being movable upon predetermined electrical conditions to trip said latch, an automatically resettable common trip member having a portion in the path of movement of said linkage mechanism and movable thereby upon the tripping of said latch,

10 means interconnecting the common trip members of the switch units so that movement of one common trip member causes the movement of the others,

each common trip member having a second portion adjacent the associated armature-like member for moving the armature-like member in the direction to unlatch its associated mechanism for opening the contacts of the switch units other than those of the switch unit which initiates the movement of the common trip member, the electromagnetic device in one of the switch units actuating said armature-like member on a predetermined decrease in energization of its associated coil.

15. The combination recited in claim 14 wherein said electromagnetic device includes a pole piece, a core movable toward and away from said pole piece, a compression spring biasing said core away from said pole piece, said core being moved toward said pole piece upon energization of said coil above a predetermined level to compress said spring and release said armature-like member, whereby upon a subsequent predetermined drop in the level of energization of said coil, said compression spring forces said core away from said pole piece and said core at such time actuates said armature-like member causing said armature-like member to trip said latch to open said contacts, said electromagnetic device further including a tube of non-magnetizable material within which said core is movable, said pole piece being secured to one end of said tube, and said compression spring being within said tube between said pole piece and said core, a connector secured to said core and extending through said pole piece, said armature-like member being biased away from said pole piece, said connector providing for joint movement of said core and said armaturelike member when said core moves away from said pole piece, but releasing said armature-like member for movement away from said pole piece when said core moves toward said pole piece.

16. The structure recited in claim 14 wherein. another of the electromagnetic devices of the switch units actuates its associated armature-like member on a predetermined increase in energization of its associated coil.

17. The structure recited in claim 16 wherein said electromagnetic device further includes a washer of nonmagnetic material between said pole piece and said core, said core seating against said washer when said core has moved its full extent toward said pole piece, said Washer is made of plastic'material capable of cushioning the impact of said core against said Washer and providing a magnetic gap between said pole piece and said core.

18. The structure recited in claim 15 wherein another of the electromagnetic devices of the switch units actuates its associated armature-like member on a predetermined increase in energization of its associated coil.

References Cited UNITED STATES PATENTS 2,912,544 11/1959 Piteo 33520 3,293,577 12/1966 Kiesel 335---20 3,369,202 2/1968 Gryctko 33520 HAROLD BROOME, Primary Examiner 

